The invention relates to an analysis system and to a method for analyzing a fluid sample on a test element, in particular for measuring the concentration of glucose in a body fluid on a test strip.
In order to analyze fluid samples, for example body fluids such as blood or urine, it is common to use analysis systems in which the samples to be analyzed are placed on a test element, typically interacting in a test field with one or more reagents on the test element before they are analyzed. The optical, e.g. photometric, and electromechanical evaluation of test elements are the most commonly used methods for rapidly determining the concentration of analyses in fluid samples. Analysis systems with test elements for fluid sample analysis are widely used in the fields of analysis, including environmental analysis as well as medical diagnosis. Test elements which are photometrically or electrochemically evaluated are of great value, particularly in the field of blood glucose diagnosis from capillary blood. Diagnostic test elements which are in the form of strips are referred to as test strips. The present invention relates to test elements of any desired shape, particularly to strip-like test elements.
For the analytical study of a fluid sample on a test element, analysis systems are known in the prior art which contain a test element receptacle for positioning the test element in a measurement position, and a measurement and evaluation device for carrying out a measurement and determining an analysis result based on this.
Primarily in the area of home-monitoring, that is to say where persons without specialist medical training carry out simple analyses of blood or of interstitial fluid themselves, such as diabetics taking blood samples on a regular basis, often several times a day, to monitor their blood glucose concentration, lancets and associated devices (so-called piercing aids) are sold that allow samples to be obtained with the least possible discomfort and in a reproducible manner.
In order to carry out the measurements, the sample is applied to an analytical test element which contains reagents (for example in a test field). When the reagents make contact with the sample, a reaction between the analyte contained in the sample and the reagents leads to a measurable change within the test element, this change correlating to the concentration of the analyte.
A measurement technique of the analysis system according to the invention is used to measure this change. The measured values obtained during the measurement method according to the measurement technique are used to determine the concentration of the analyte in the sample.
A suitable analysis system may be designed to carry out an electromechanical and/or photometric analysis. In photometric analysis systems, the test elements contain a reagent system whose reaction while the analyte leads to a photometrically detectable change (e.g. a change in color). In this case, the reagents are usually located in a test field of the test element, with the photometrics (e.g. color) of the reagents changing as a function of the concentration. This photometric change can be quantitatively determined, for example, by reflection photometry with the aid of a suitable measurement technique.
Electromechanical test elements contain an electromechanical reagent system in which one or more reactions with the analyte influence the electrical voltage applied between two poles of the test element and/or the current flowing between two poles of the test element at a defined voltage. As a result, the voltage or the current is therefore the measurable change which is determined by a suitable measurement technique, which is integrated in the analysis system and is designed as a voltage- or current-measuring device, and whose change, which correlates to the concentration of the analyte, is converted into analysis data (concentration of the analyte).
Many such known analysis systems are produced in complicated and costly manner from a large number of individually manufactured parts which then have to be assembled. In particular, the arrangements known from the prior art for positioning and locking test elements in an analysis position usually comprise a plurality of individual injection-moulded plastic parts and spring elements. The separate production processes and the assembly of the individual parts are costly and lead to more limiting tolerances in the basic positioning of the test element in the measurement and evaluation device. These parts usually correspond to the device housing structure, with the result that several interrelated tolerance factors have to be taken into account with respect to measurement accuracy, and this in turn leads to high costs on account of highly precise parts and processes.
The object of the invention is therefore to avoid the disadvantages of the prior art systems and, in particular, to provide an analysis system with cost-effective components, in particular with a cost-effective test element receptacle for positioning and locking a test element in an analysis position in the measurement and evaluation device.